Sheet material for printing and writing purposes and the like comprising a synthetic fiber fabric



Sept. 26, 1961 M` NoBERAsco 3,001,263

SHEET MATERIAL FOR PRINTING AND WRITING PURPOSES AND THT LIKE coMPRTsTNG A SYNTHETIC FIBER FABRIC Filed Deo. 20. 1955 United States Patent 3,001,263 SHEET MATERIAL FGR PRINTING AND WRITING PURPOSES AND THE LIKE COMPRISING A SYN- THETIC FiBER FABRIC Massimiliano Noberasco, Milan, Italy, assigner to Snia Viscosa Societ Nazionale Industria Applicazioni Visn cosa- Societ per Azioni, Milan, Italy Filed Dec. 20, 1955, Ser. No. 554,320 Claims priority, application Italy Dec. 23, 1954 4 Claims. (Cl. 28-7-4) The main object of `this invention to provide a sheet material adapted to be printed and used as paper substitute, affording a number of advantages over paper, as it is not liable to deteriorate in contact with water nor take fire or burn, is acid-proof and its tensile strength is so high that it can be regarded as actually inde- 'structible p An article of this kind, which is of paper-like appearance, is particularly useful. in manufacturing and processing valuable documents such as bank-notes and the like, andparticularly articles which are highly desirable to preserve in an unalteredv condition. i

The improved article is prepared from a polyamid fabric, such as those known under the trade lnames of nylon. Perlon or Lilion which are poloymers of caprolactam and are generically known as ynylon 6, or an acrylic fiber such as Orion may be used. The fabric may be either plain or complex interlacing, in accordance with requirements, and may be manufactured from threads of anyV desired gauge.

The yfabric is iirst secured and bleached, dyed if desired by any known preferred method, then heat-treated at a` temperature such as to Ibring the libres of which it is composed to their incipient melting point. More particularly, vthe fabric is treated `at a temperature ranging between 150 and 300 C.

The fabric is then coated on both faces by one or more layers of a polymer composition of a suitable type se leeted in accordance with the use for which the fabric is intended.

Acrylic, polyvinyl, melamine and polystyrene resins and acetates have been found particularly useful.

The layers may be of the same or different types of resins.

The. fabric is then calendered, preferably with frictional eiiect. The temperature of the heated calen'dering roll andV roll pressure are adjusted in accordance with destination of the article.

The resins for coating the fabric may be previously adrnixed with iilling materials, more particularly colored pigments, in order to give to the final product. the desired coloring opacity. For instance, in order to make the product white or of another ground color, the resin for coating the fabric is previously admixed with a filler which is white or of the desired color.

The. additions are particularly intended to improve opacity,4 hence resemblance of the article. to paper, as well'4 as its ink acceptance. In addition or instead of' pigment fillers, other fillers may be added as required by the destination of the article.

The calendered material may be wound up in rolls like paper and used as a paper substitute with. the above. de'- seribed advantages..

As mentioned above the resins may -be ofvarious types according to the intended use of the article. For instance, articles intended as paper substitute to be printed with conventional printers inksV are obtained by coating a suitable fabric with a plurality of layers of synthetic resins.

It s understood that the libres of which the` fabric is composed, the thread gauge and type of resin employed for successively coating the fabric may vary without departing from the scope of this invention.

in order that the invention may be more clearly under-stood one construction in accordance therewith will now be described by way of example with reference to the drawings and appended examples Aof the method of manufacturing sheets suitable for printing more particularly on rotary printing machines `by means of pigmented inks with solvents as xylene, benzene and the like,.and material for banknotes and the like.

In the drawings:

FIG. 1 is a cross-sectional view on an enlarged scale of a fabric;

FIG. 2 is a similar cross-sectional view of the fabric in FIGURE 1 after calendering;

FIG. 3 is a diagrammatic side View of a machine for coating the fabric shown in FIGURES 1 and 2;

FIG. 4 is a cross-sectional view of the fabric shown in FIG. 2 after coating.

Example 1 Warp: opaque Lilion 60 denier, l2 lilaments, 1.50 turns per meter sized 52 threads per centimeter,

Wett: opaque Lilion 60 denier, l2 filaments, 150 turns per meter sized 40 threads per centimeter.

This fabric is scoured 1by conventional means in order fully to remove foreign Abodies such as sizing matter from the threads.` The fabric is then dried and caulked in. a

drying machine, wound to rolls or directly transferred tov the next processing step consisting in calendering. The calender is preferably of the three-roll type, tw'orside rolls being lined with very stiff wool-paper, the central roll being of steel and equipped with heating means. The pressure between the rolls is maintained at about 5,0()0 kgs., the temperature of the central roll being set at about 190 C., at any rate not to exceed 215 C.

Calendering is carried out at increasing speed' of the successive rolls in order to draw the libres as theyV are heated to their incipient melting point. This step of. the process depletes the fabric of its original properties by converting it to an endless web or sheet in which the threads composing the original fabric have been. mutually sealed. The interlacing of the threads before and. after calendering is sho-wn on a strongly enlarged scale in FIGURES l and 2, respectively. In these gures, 10 and li denote weft and warp threads, respectively. In FIGURE Z the flattening of the weft and warp threads resulting `from high temperature calendering is visible, the sheet surface, while still showing the pattern of the original fabric, being highly equalized. In these figures the seal between the individual weft and warp threads has not been shown for the sake of clearness'.

The resulting endless web is wound on to rolls and allowed to stand at least 24 hours in order to allow' the bres to set and cure after heat treatment.

The web is then coated. The machines employed for coating may comprise a doctor-blade machine ofthe type diagrammatically shown on FIGURE 3 in which 20, 21, 22 denote the delivery and drying sections. and a winding device, respectively. The web F is unwound from the roll 24 and guided past a coating unit 25 vcomprising two doctor-blades, not shown, adapted to spread the coating material on the top face of the web. The web coated on one side enters the drying chamber 2l in a horizontal direction, is moved back once over the idle roller. 26

Patented Sept. 26, 1961 i situated at the outlet end of the chamber 21, then over the rollers 27 situated at the inlet end of the chamber 21 and removed onthe right-hand side of the gure. The dhamber 21 is about 5 meters long, the web length in the drying chamber being about l meters long. The chamber 21 is equipped with means for heating and circulating hot air (not shown) adapted to supply about 5 cubic meters per minute hot air at a temperature of .about -l00 C. The rate of travel or" the web F through chamber 21 is 6-7 meters a minute. Consequently, a given web portion dwells in chamber 2i about 2.5 minutes.

The winding device 22 comprises two water-cooled cylinders '28, 2.9 over which the web F travels before it isk Wound to a collecting roll 30. Upon completion of the coating step on one web face, the roll 30 is transferred ,to the delivery section Z0 for coating the other face by the same coating material under the similar conditions.

Ihe composition of the coating material for forming the rst" coating layer on both lweb faces is as follows:

L Parts Acronal 500L (Badische Anilinund Soda-FabrikLnZS Solvent (acetone or ethyl acetate) FIG. 4. The figure is a cross-section taken parallel to the warp at any point of the fabric. Therein l0 and il ,again designate the weft and warp threads. The iirst coating layer is indicated by the numerals l2 and 13 respectively on the upper and lower face of the material.

Second layers 14 and 15 are shown as respectively applied to the upper and lower face. A third layer lo is shown as applied only to the upper face. As seen, the coating substantially lls the recesses in the reticular structure of the fabric, but its thickness is less on the raised portions of the thread, and might even be much .less than shown on the drawing for purposes of illustration. Coating layers i2 and i3 penetrate in the interstices of the fabric. In the drawing they are shown as filling said interstices, but in practice some voids may remain and the separation line between the two coatings will not be as sharp and regular as shown for purposes of illustration.

Depending upon the final destination of the web, the coating material for forming the layers successively to the rst layer is admiXed with suitable illers and coloring matter. In this case, the composition of the coating material is as follows:

Parts Lutofan 200L (Badische Anilinund Soda-Fabrik) 12 Calcium carbonate 6 High-grade lithopone white 6 Solvent (acetone or ethyl acetate) 76 Since only one coating or layer has been applied to the fabric before it reaches the stage represented in FIG. 4, the threads are not entirely covered with coating but the coating substantially fills the' recesses in the reticular structure of the fabric. Thus a considerable thickness of resin has been built up at 14 and l5, While adjacent these spaces the threads are partly uncovered.

The above mentioned ingredients are mixed in a tightly-sealed mixer during at least 24 hours. :mass is further reiined in a lcylinder refining machine and `tiltered at least twice, whereupon it is ready for spread- The resulting p 4 ing in the above described manner. Upon completion of the coating and iinal web weight checking steps, the web is cured in a dry enclosure during at least 48 hours, whereupon it is calendered. This end step is carried out to make the surface of both faces fu-lly smooth or goiered, as desired. The temperature of the heated roll should not exceed 50-60 C., pressure amounting to about 3,000 kgs. The calendering rate is 6-7 meters a minute. The end product can be advantageously employed lfor rotary recess printing, or cut to separatesheets and printed in the known manner like paper.

Example 2 In order to prepare a web suitable for bank-notes a fabric of polyamide fibre is provided such as Lilion manufactured by Snia Viscosa, of plain weave type of the following properties:

Vllfarp:` opaque Lilion, 30 denier, 10 l-aments, 150 turns per meter, sized 45 threads per centimeter. ,Y

Weit: opaque Lilion, 30 denier, l0 filaments, 150 turns per meter, sized 40 threads per centimeter.

The web s processed as in Example 1 with the difference that the rst coating layer is applied to each web face and drying is carried out at a rate of 4 meters per minute, nal calender-ing being effected in the following manner.

The calender comprises an engraved roller heated to about i-210 C. 'Ihis roller is made of bronze and is about 200 millimeters in diameter. Before reaching the bronze roller the web is calendered between a steel roller 220 millimeters diameter and a roller lined with woolpaper 440 millimeters in diameter at a rate of `5-15 meters per minute ata pressure of about 20 tons. When a silk-finish of the web is desired, pressure should be raised to 30 tons, the diameters of the steel and Woolpaper lined rollers being then 240 and 480 millimeters, respectively. The travel rate should be raised to 30 meters per minute. The result is a pattern on the web resembling water-marked paper used in bank-notes, the said pattern being practically indelible. A last normal calendering step completes the process.

What I claim is:

1. A sheet material Kfor use as a paper substitute comprising a fabric of a synthetic linear polymer chosen from the group consisting of polyamide and acrylic fibres, said fabric having weft and 'warp threads fused to one another at points of interlacing of the threads; a coating layer of synthetic resin on each face of the fabric; and at least one further coating layer superposed on at least one of the first named layers, said further layer comprising synthetic resin admixed with a coloring pigment filler.

2. Method of manufacturing a sheet material for use as a paper substitute comprising providing a fabric having weft and warp threads of a linear synthetic polymer chosen from the group consisting of polyamide and acrylic bres; scouring the fabric for substantial removal therefrom of any substance other than the polymeric fibre material; drying the fabric and calendering it at a temperature between and 300 C. and at a rate suiicient to 'bring the weft and Awarp threads to their incipient melting point whereby they are mutually sealed; coating both faces of the resulting sheet with a synthetic resin and thereupon coating at least once more at least one face of the sheet with a further synthetic resin layer containing a coloring pigment filler; drying eac-h time the coating layer applied and finally calendering the coated sheet.

3. A sheet material for use as a paper substitute comprising a fabric of synthetic polyamide fibre, said fabric having weft and warp threads fused to one another at points vof interlacing of the threads; a coating layer of v 'synthetic resin on each face of the fabric; and at least one further coating layer superposed on at least one of the first named layers, said further layer comprising synthetic resin admixed with a coloring pigment ller.

4. Method of manufacturing a sheet material for use as a paper substitute comprising providing a fabric having weft and Warp threads of a synthetic linear polymer chosen from the group consisting of polyamide and acrylic fibres; scouring the fabric for substantial removal therefrom of any substance other than the synthetic fibre material; drying the fabric and calendering it at a temperature and rate sucient to bring the weft and Warp threads to their incipient melting point whereby they are mutually sealed; coating both faces of the resulting sheet with a synthetic resin layer and thereupon coating at least once more `at least one face of the sheet with a Vfurther synthetic resin layer containing a coloring pigment ller; drying each time the coating layer applied and nally calendering the coated sheet.

References Cited in the file of this patent UNITED STATES PATENTS Mork May 27, Lindsay May 19, McBurney et al Oct. 5, Thinius Aug. 17, Dorough et al. Oct. 19, Barnard Aug. 1, McFarlane Oct. 10, Kallmann Aug. 7, Grupe Mar. 19, Lord et a1. May 28, Duggan J-une 29, Wurzburger Jan. 9, Farnwoith et al. Dec. 11, Schlatter Dec. 29, Meherg et a1 May 25,

Arledter Oct. 18, 

4. METHOD OF MANUFACTURING A SHEET MATERIAL FOR USE AS A PAPER SUBSTITUTE COMPRISING PROVIDING A FABRIC HAVING WEFT AND WARP THREADS OF A SYNTHETIC LINEAR POLYMER CHOSEN FROM THE GROUP CONSISTING OF POLYAMIDE AND ACRYLIC FIBRES; SCOURING THE FABRIC FOR SUBSTANTIAL REMOVAL THEREFROM OF ANY SUBSTANCE OTHER THAN THE SYNTHETIC FIBRE MATERIAL; DRYING THE FABRIC AND CALENDERING IT AT A TEMPERATURE AND RATE SUFFICIENT TO BRING THE WEFT AND WARP THREADS TO THEIR INCIPIENT MELTING POINT WHEREBY THEY ARE MUTUALLY SEALED; COATING BOTH FACES OF THE RESULTING SHEET WITH A SYNTHETIC RESIN LAYER AND THEREUPON COATING AT LEAST ONCE MORE AT LEAST ONE FACE OF THE SHEET WITH A FURTHER SYNTHETIC RESIN LAYER CONTAINING A COLORING PIGMENT FILLER; DRYING EACH TIME THE COATING LAYER APPLIED AND FINALLY CALENDERING THE COATED SHEET. 